This invention relates to a stripping tool for removing a sheath or covering from a conductor and, more particularly, to a tool for removing the sheath from a fiber optic conductor.
Fiber optic cables are assembled to form a fiber bundle which, to protect it against mechanical damage, is introduced into a flexible metal or synthetic plastic hose. The installation of such cables requires splicing together of cable sections which, in turn, involves cutting the hose and splitting the fiber bundle to expose the individual glass fibers, which have a sheath or covering that must be removed preparatory to splicing to another fiber. More particularly, an optical coupler is used to splice two optical fibers together, and preparatory to inserting their ends into the coupler a predetermined length of the sheath of each is removed and the fiber itself cut off squarely. The sheath typically is a silicon coating having a thickness on the order of 0.025 mm and therefore is very fragile, the fibers themselves are fragile and easily damaged, and often the stripping and splicing must be done in confined quarters. Accordingly, there is a need for a small, easily manipulable tool which is suitable for stripping the fragile sheath from an optical fiber without nicking or otherwise mechanically damaging the fiber.
Among the known tools heretofore used for this purpose is the hand-held stripping tool described in U.S. Pat. No. 4,748,871. The disclosed tool has two like components pivoted together between their ends so as to provide a pair of rigid lever handles on one side of the pivot and a pair of jaws on the other side of the pivot; a portion of each jaw near the pivot is flexible and resilient. Each jaw is provided with a blade which project toward one another and include faces which are parallel to each other and contact the sheath when the lever handles are pressed together. Should excess pressure be applied when closing the blades on the sheath, the flexible portion of the jaws flex thereby to minimize the risk of fiber damage. The tool effectively self-adjusts to the sheath characteristics, a sheath that severs easily will do so under light pressure before much flexure of the jaws has occurred, while one which is tougher will require greater pressure and flexing.
From the analogous art of wire strippers, U.S. Pat. No. 2,894,424 discloses a tool consisting of two resilient bars connected together at one end and adapted to be compressed toward one another. A pair of transverse cutter blades are fixed to the free ends of the bars, the blades having coacting V-shaped cutting edges for straddling the sheathing of a wire. In use, the bars are compressed and the tool rotated about the axis of the wire to cut a ring transversely in the sheathing to separate a portion of the sheathing by pulling the blades along the wire. An adjustable stop mounted on one of the bars and disposed between the pair of bars limits the compression of the bars so as to prevent the blades from cutting into the conductor. This stripper does not self-adjust to the diameter of the optical fiber, but must be set by the user, which can lead to application of excess pressure and breakage if used to remove sheath material from a fragile glass fiber. Moreover, the V-shaped cutting edges do not allow for sideways deformation of the sheathing material as the bars are compressed toward one another, which would increase the risk of breakage if used to strip an optical fiber.
The object of the present invention is to provide an improved tool for stripping the sheath from an optical fiber without nicking or otherwise mechanically damaging the fiber core.
Another object of the invention is to provide such a tool which is small enough to be conveniently used in close quarters.
Still another object of the invention is to provide such a tool which is relatively easy and inexpensive to manufacture.